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PubMed1991

[Lead placental transfer and metals content in biosamples from occupationally lead exposed female workers].

This paper presents a study of five metals content in biosamples of placenta, maternal venous blood, cord blood from 32 occupationally lead exposed female workers and 32 controls. The results showed that lead levels in biosamples of lead exposed individuals were significantly greater than those from controls. Results also showed that there existed very close relationships between placental lead and maternal blood lead, placental lead and cord blood lead, maternal blood lead and cord blood lead, showing that there was a lead transfer from the mother to the child via the placenta. The relationships between metals in the biosamples were also discussed in the paper.

Adult↗
PubMed1986

Lead neuropathy and electrophysiological studies in low level lead exposure: a critical review.

The literature on nerve conduction velocity (NCV) studies and electromyography in lead exposed populations was reviewed. All studies revealed some degree of defect in their experimental design. Disregarding these limitations, a consensus of the studies indicates that a mild slowing (7%) of motor and sensory NCV may be present in the median and posterior tibial nerves, but that ulnar and peroneal NCVs are not slowed in subjects with blood lead levels of less than 60 micrograms/dl. No clinical correlations to this mild slowing were reported in studies where concurrent motor and sensory examinations were performed. A majority of the studies did not find a correlation between blood lead level and NCV at blood lead levels below 70 ug/dl or length of exposure and NCV. Most studies of electromyographic activity in lead exposed population found abnormalities only in patients with blood lead levels above 60-70 ug/dl or in patients with lead colic or other systemic symptoms of lead intoxication. This review does not find evidence that the slowing of NCV in low level lead exposure is clinically significant or evidence that would suggest that it is a subclinical manifestation of clinical lead neuropathy in man.

Animals↗
PubMed1988

Blood lead levels in children living in three communities, at different risks of lead pollution.

We carried out a survey on blood lead levels in children living in three different communities in Umbria, Italy: Corciano, a small community (12,500 inhabitants), free of lead-using factories and with light traffic; Perugia, a medium-sized city (146,500 inhabitants); Deruta, a small community (7500 inhabitants) whose economy is based mainly on the production of artistic pottery, mostly in small home-operated factories. The study sample was made up of 539 children (275 boys and 264 girls); 156 of them attended nursery school (aged 3-6) and 383 primary school (aged 6-11). The mean blood lead level was significantly higher in Deruta than in Corciano (9.7 vs 8.3 micrograms/dl); Deruta children whose parents were occupationally exposed to lead had significantly higher blood lead levels than children of lead-unexposed parents (10.7 vs 9.0 micrograms/dl). The mean blood lead level was higher in Perugia than in Corciano children. On the average boys had higher blood lead levels than girls in all of the groups. We conclude that blood lead levels were low in the groups of children studied. Nevertheless children of ceramic workers and children living in a medium-sized city had greater lead absorption than children living in the control area.

Child↗
PubMed1980

[Effect of the lead-petrol-law on the contents of lead and benzo(a)pyren in urban environmental dust (author's transl)].

For the purpose of evaluating the stress on citydwellers by pollutants emanating from traffic sources the contents of lead and 3,4-benzpyrene in sedimentable city dust were determined in samples collected at 46 sites with different traffic densities in a city of medium size but considerable overall traffic volume (Erlangen, Bavaria). To estimate the effect of the gasoline-lead-law of Aug 5, 1971, determinations were carried out both in 1971, i.e. before this law came into effect, and in 1977 when the lead content in gasoline was finally limited to 0.15 g/1. The following results were obtained: - In city areas with dense traffic, the medium lead content dropped from 4.2 to 2.2 mg/g of dust, and the medium 3,4-benzpyrene concentration dropped from 1.3 to 0.5 microgram/g of dust. This amounts to a reduction of both the lead and 3,4-benzpyrene contents in city dust by about one half. - In the city periphery with lesser traffic density, the lead and benzpyrene contents, resp., were originally lower by about one half. In the case of lead, the concentration dropped from 1.9 mg to 1.2 mg/g dust, while 3,4-benzpyrene dropped from 0.6 to 0.4 microgram/g dust. Thus, the beneficial effect of the gasoline-lead-law was less obvious in these low-traffic parts of the city area. - The decrease in 3,4-benzpyrene with decreasing lead content is remarkable (striking, a striking pheromeron) and may be explained by lesser emission of this pollutant when burning gasoline low in lead.

Automobiles↗
PubMed1995

[Screening for lead poisoning in children by measuring lead levels in housing: a study of the Paris region].

Screening programs for lead poisoning in France rely usually on the preliminary identification of risk factors among children seen in Maternal and Child Health (MCH) clinics. To assess the potential relevance of screening strategies based on the quantification of exposure to lead in housing, we estimated first the prevalence of exposure to lead in a representative sample of older buildings, then the prevalence of lead poisoning among children living in those buildings where high levels of lead had been found. Exposure to lead was measured in dust and paint samples collected in hallways and other collective areas of the buildings. Venous blood samples were collected from the children aged 10 months to 6 years residing in buildings where lead exceeded 1.5 g/kg in paint samples or 1000 micrograms/m2 in dust samples. Paint and dust samples were collected in 137 buildings: 74% presented high dust and/or paint lead contents. Blood samples were collected from 145 out of a total of 189 children residing in these buildings: blood lead levels (PbB) were higher than or equal to 10 micrograms/dl for 65% of these children; 29% were higher than or equal to 15 micrograms/dl, 16% higher than or equal to 20 micrograms/dl. Out of 42 children with PbB > or = 15 micrograms/dl, 21 had not been previously identified through the screening program conducted in local MCH clinics. Clinic-based and environment-based screening appeared to be complementary. It seems thus justified to develop screening strategies based on the assessment of exposure to lead in the environment.

Child↗
PubMed1998

[Removal of the endocardial pacemaker leads--experience with 16 leads in 10 patients].

Recent advances in pacemaker leads have contributed to the improvement of their stability at the anchored sites. However, we sometimes have difficulty in removing them. We have experienced the removal of 16 leads in 10 patients (male: 7, female: 3) in the last 5 years. The age of patients ranged from 48 to 87 years, and the average was 60. The reasons for the removal were as follows; pocket infection in 6 cases, sepsis in 1 case, ischemic skin erosion in 1 case, retained fractured ventricular lead in 1 case, fracture of Accufix atrial lead in 1 case. The methods of removal consisted of using the removal kit, the snare or the basket snare transvenously, direct surgical approach or a combination of them. We used the removal kit alone in 12 electrodes (6 atrial, 6 ventricular), and removal of 5 atrial and 3 ventricular leads were successfully by this method only. The removal of 4 leads by kits alone failed, so that 2 ventricular leads were removed transvenously, one atrial and one ventricular lead were removed surgically, and 1 ventricular lead was left untreated. Finally, we were able to remove 15 of 16 leads (93.3%) successfully. This experience indicates that these interventions should be performed as less invasively as possible, yet we should give an explanation to the patients as to the options we may employ when we have failed in the intended procedure.

Aged↗
PubMed1994

Improved detection of transient myocardial ischemia by a new lead combination: value of bipolar lead Nehb D for Holter monitoring.

The investigations of ST-segment changes by Holter monitoring demonstrate asymptomatic and symptomatic episodes of myocardial ischemia, which may occur during daily activities. One factor, which is of great importance for the detection of silent myocardial ischemia during ambulatory monitoring, is the combination of the leads. Former studies showed that the analysis of two channels alone may not adequately detect silent myocardial ischemia. We therefore used a three-channel ambulatory ECG monitoring system with a new lead combination. The Holter monitoring results were correlated with the distribution of coronary stenosis detected by coronary angiography. In 54 patients with single coronary vessel disease and ischemic ST-segment depressions during exercise testing, standard Holter lead combination CM2/CM5 was extended by a bipolar Nehb D-like lead. Lead combination CM2/CM5 identified 23 patients (43%) with ST-segment depressions (total number of ischemic episodes = 372). Additional Nehb D-like lead identified 30 patients (55%) with ST-segment depressions (total number of ischemic episodes = 1048). The combination of leads CM2/CM5 and Nehb D raised the number of patients with documented ST-segment depressions to 33 of 54 (61%). Lead Nehb D showed the highest sensitivity for the detection of inferior wall ischemia (stenosis of the right coronary artery); nevertheless, this lead may not be regarded as specific for ST-segment alterations only caused by inferior wall ischemia. The correlation of ischemic ST-segment depressions during exercise testing (classified as anterior, inferior, or anterior and inferior type of ischemia) and documented ST-segment changes in the different Holter leads underline these results.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1995

Postoperative lead-related complications in patients with nonthoracotomy defibrillation lead systems.

OBJECTIVES: This study sought to document postoperative complications attributable to nonthoracotomy defibrillation lead systems in a large cohort. BACKGROUND: The incidence of postoperative complications specifically associated with nonthoracotomy defibrillation lead systems is unknown. METHODS: Postoperative lead-related complications were evaluated in 170 patients with a nonthoracotomy defibrillation lead system who were followed up for a mean (+/- SD) of 17 +/- 12 months. Each system incorporated one or more intravascular leads. In 117 patients (69%), the system incorporated a subcutaneous defibrillation patch. All implantations were performed in an operating room by cardiothoracic surgeons. Defibrillation thresholds were measured at implantation, before hospital discharge (mean 3 +/- 2 days) and at 4 to 18 weeks after implantation. Patients were evaluated every 2 to 3 months after implantation or as indicated by clinical exigency. RESULTS: Twenty-seven patients (15.9%) were diagnosed with a lead-related complication that either extended the initial hospital period or led to a second hospital admission. Complications included endocardial lead or subcutaneous defibrillation patch dislodgment in eight patients (4.7%), which was diagnosed between 2 and 345 days after implantation; endocardial or subcutaneous patch lead fracture in six (3.5%), which was diagnosed between 53 and 600 days after implantation; subcutaneous patch mesh fracture in one, which was diagnosed at 150 days after implantation; subclavian vein thrombosis in three (1.8%), which was diagnosed at 2 to 50 days after implantation; and unacceptably elevated defibrillation threshold (within 5 J of maximal device output) in nine (5.3%), which was documented at one of the two postimplantation evaluations in eight patients or at the time of failure to terminate a spontaneous ventricular tachycardia in one. Seventeen of the 27 patients required reoperation for correction of their complication. In addition, system infection requiring complete explantation occurred in seven other patients (4.1%) at an interval from implantation ranging from 14 to 120 days. CONCLUSIONS: Postoperative complications related to a nonthoracotomy defibrillation lead system were common and frequently required reoperation for correction. The rate of system explantation due to infection was also significant. Postoperative defibrillation testing and vigilant outpatient follow-up evaluation are necessary to ensure normal lead function.

Binomial Distribution↗
PubMed2005

Current of injury predicts adequate active lead fixation in permanent pacemaker/defibrillation leads.

OBJECTIVES: The aim of this study was to determine whether current of injury can guide adequate placement of active-fixation pacing leads. BACKGROUND: Active-fixation leads cause injury to the myocardium at the time of fixation, manifested as a current of injury (COI) that may result in acute elevation of pacing thresholds. The relationship of COI to subsequent improvement in pacing thresholds is not clear. METHODS: Sixty-five patients undergoing active-fixation lead implantation were enrolled. Current of injury was characterized as the duration of the intracardiac electrogram (EGM) and the magnitude of ST-segment elevation. Pacing parameters were measured up to 10 min after fixation. RESULTS: A total of 96 active-fixation leads were studied, and 76 leads had a current of injury. From baseline to the time of fixation, the duration of the intracardiac EGM in ventricular leads increased from 150 +/- 31 ms to 200 +/- 25 ms (p < 0.001), and the ST-segment increased from 1.5 +/- 0.2 mV to 10.0 +/- 2.0 mV (p < 0.001), with subsequent improvement in pacing thresholds from 1.5 +/- 0.4 V to 0.8 +/- 0.3 V (p < 0.001) at 10 min. Atrial leads with a current of injury had similar findings. Of the 20 leads without a COI, 5 dislodged acutely and 15 had high pacing thresholds at 10 min, requiring repositioning. CONCLUSIONS: The development of a COI indicates that within 10 min of fixation, pacing threshold will return to an acceptable range even if the initial measurement is high. Conversely, without a COI, lead fixation is not adequate and the lead should be repositioned.

Aged↗
PubMed1999

Accuracy of the EASI 12-lead electrocardiogram compared to the standard 12-lead electrocardiogram for diagnosing multiple cardiac abnormalities.

This study was performed to compare a derived 12-lead electrocardiogram (ECG) using a simple 5-electrode lead configuration (EASI 12-lead) with the standard ECG for multiple cardiac diagnoses. Accurate diagnosis of arrhythmias and ischemia often require analysis of multiple (ideally, 12) ECG leads; however, continuous 12-lead monitoring is impractical in hospital settings. EASI and standard ECGs were compared in 540 patients, 426 of whom also had continuous 12-lead ST segment monitoring with both lead methods. Independent standards relative to a correct diagnosis were used whenever possible, for example, echocardiographic data for chamber enlargement-hypertrophy, and troponin levels for acute infarction. Percent agreement between the 2 methods were: cardiac rhythm, 100%; chamber enlargement-hypertrophy, 84%-99%; right and left bundle branch block, 95% and 97%, respectively; left anterior and posterior fascicular block, 97% and 99%, respectively; prior anterior and inferior infarction, 95% and 92%, respectively. There was very little variation between the 2 lead methods in cardiac interval measurements; however, there was more variation in P, QRS, and T-wave axes. Of the 426 patients with ST monitoring, 138 patients had a total of 238 ST events (26, acute infarction; 62, angioplasty-induced ischemia; 150, spontaneous transient ischemia). There was 100% agreement between the 2 methods for acute infarction, 95% agreement for angioplasty-induced ischemia, and 89% agreement for transient ischemia. EASI and standard 12-lead ECGs are comparable for multiple cardiac diagnoses; however, serial ECG changes (eg, T-wave changes) should be assessed using one consistent 12-lead method.

Aged↗
PubMed1984

Novel oligosaccharide chains on polysialoglycoproteins isolated from rainbow trout eggs. A unique carbohydrate sequence with a sialidase-resistant sialyl group, DGa1NAc beta 1 leads to 4(NeuGc2 leads to 3)DGa1NAc.

A series of novel carbohydrate chains all possessing a hitherto unknown trisaccharide unit, Ga1NAc beta 1 leads to 4-(NeuGc2 leads to 3)Ga1NAc beta 1 leads to, have been isolated from trout egg polysialoglycoproteins, a new class of glycoproteins, on alkali-borohydride treatment. On the basis of chemical (methylation, Smith degradation, and hydrazinolysis-nitrous deamination) and direct-probe mass spectrometric methods. deamination) and direct-probe mass spectrometric methods, the structures of a series of the first major type of oligosaccharide alditols having a sialidase-resistant N-glycolyneuraminic acid residue in each molecule were determined. The structures thus determined are novel and all possess a unique carbohydrate sequence (sialidase-resistant unsubstituted sialyl group italicized): Ga1NAc beta 1 leads to 4(NeuGc2 leads to 3)Ga1NAc beta 1 leads to 3Gal beta 1 leads to-4Gal beta 1 leads to 3[(leads to 8NeuGc alpha 2)n leads to 6]Ga1NAcol (n = 0 through 3).

Animals↗
PubMed2003

Nonthoracotomy implantable defibrillator lead extraction: results and comparison with extraction of pacemaker leads.

Extraction of pacemaker leads has been demonstrated to be successful and safe in experienced hands using current tools. Whether application of such techniques and tools yield similar results among patients undergoing extraction of nonthoracotomy implantable defibrillator leads is unknown. This report describes a retrospective analysis of indications, techniques used, and outcome of patients who had a single ventricular nonthoracotomy implantable defibrillator lead extracted at The Cleveland Clinic Foundation. Results were compared to a matched population of patients undergoing extraction of ventricular pacemaker leads from a national registry and to the experience with pacemaker lead extraction at The Cleveland Clinic Foundation. Successful complete extraction of ventricular nonthoracotomy implantable defibrillator leads, in the absence of major complications, was achieved in 96.9% of attempts to extract leads from 161 patients. Clinical success was achieved in 98.1% of patients. Failure occurred in three patients. Two patients had major complications, including one death. The most common indication for extraction was infection (46.6%), followed by lead failure (34.2%). Procedure (140.8 vs 171.2 minutes, P<0.01) and fluoroscopy (9.9 vs 11.0 minutes, P<0.01) times compared favorably with those obtained from the pacemaker lead extraction database. Use of LASER did not influence the safety of the procedure or fluoroscopy times. Extraction of ventricular nonthoracotomy implantable defibrillator leads using currently available tools is a complex but effective procedure. In experienced hands, excellent success rates should be achieved with a low incidence of complications.

Adolescent↗
PubMed1983

Comparison of lead complications with polyurethane tined, silicone rubber tined, and wedge tip leads: clinical experience with 822 ventricular endocardial lads.

Lead-related complications have been prospectively studied for 602 unipolar tined endocardial ventricular pacemaker leads implanted over a five-year period. No differences were noted in overall complication rates between 238 polyurethane insulated leads (4.2%) and 364 silicone rubber insulated leads (3.6%). Comparing the total series of 602 tined leads to a retrospective survey of 220 wedge tip leads, a marked reduction in dislodgements (0.3% vs. 7.7%, P less than 0.001) and reoperations (2.0% vs 15.0%, P less than 0.001) was found using tined leads. We conclude that tined ventricular leads are far superior to wedge tip leads with respect to lead complications.

Arrhythmias, Cardiac↗
PubMed1990

Steroid-tipped leads versus porous platinum permanent pacemaker leads: a controlled study.

There is little data directly comparing steroid-tipped permanent pacemaker leads to otherwise state-of-the-art porous platinum leads. Eighteen patients receiving unipolar generators capable of low voltage outputs were randomized at the time of implant to receive either steroid-tipped leads or porous platinum leads. All leads were unipolar, tined, passive fixation, and placed in the right ventricular apex or atrial appendage. This study is single center. At implant, threshold pulse width was determined at 3 voltages (2.5, 1.5, and 0.8 V). Follow-up thresholds were determined at weeks 1, 2, 3, and 4, and at 3 and 6 months. There was no difference in implant thresholds or amplitudes for sensing. By 2 weeks postimplant, lower thresholds were noted for the steroid leads, and this discrepancy grew more significant with time. There was no significant postimplant rise in threshold for steroid-tipped leads. At 6 months, the average threshold pulse width for ventricular steroid leads at 0.8 V was 0.3 +/- 0.1 msec. In contrast, five patients with standard leads did not capture at maximum pulse width at 0.8 V (P less than 0.0001). There was no significant difference in the amplitude of the chronic atrial electrogram. This study shows steroid-tipped leads to offer a significant advantage in reducing thresholds early postimplant and chronically.

Aged↗
PubMed1996

Electrophysiological characteristics of bipolar membrane carbon leads with and without steroid elution compared with a conventional carbon and a steroid-eluting platinum lead.

In a controlled study, the following four bipolar leads with passive fixation were implanted in 46 patients with the Siemens-Multilog-VVI or Sensolog-VVIR-pacemakers: membrane covered activated porous carbon with steroid elution (Siemens 1402 T, 11 patients) and without (Siemens 1403 T, 15 patients); activated carbon (Siemens 1010 T, 10 patients); and platinum with steroid elution (Medtronic Cap-Sure 5026, 10 patients). Stimulation threshold (STH) (assessed by a vario-test), impedance (IMP), and the intracardial R wave potential (IRW) (both gauged by a telemetric method) were measured 1, 5, and 10 days as well as 3 and 6 months after implantation during unipolar and bipolar stimulation, chronaxie rheobase product (CRP) and energy consumption (EC) were systematically determined. Differing insignificantly at the first day after implantation, STH is significantly lower for the 1402 T and CapSure 5026 leads at the tenth day. However, the 1402 T lead shows a significant increase of STH in the follow-up, in contrast to the other leads. The lowest chronic STH was found in the CapSure 5026 lead (CRP is significantly lower in all other leads, too). IMP is significantly lower in the CapSure 5026 lead compared to 1010 T lead. EC does not differ significantly during chronic stimulation in spite of the best possible programming of pulse amplitude and duration. No significant changes of IRW were observed. Unipolar versus bipolar stimulation shows significantly lower STH, CRP, and IMP, differences of EC and IRW were insignificant. In conclusion, the addition of steroid in membrane covered carbon leads protracts the increase of STH, but does not prevent it. The CapSure 5026 lead shows advantageous stimulation characteristics, but energy consumption is not significantly reduced because of low impedance and impossibility of programming an appropriate low output in Multilog pacemakers.

Aged↗
PubMed2006

Transvenous pacemaker lead removal is safe and effective even in large vegetations: an analysis of 53 cases of pacemaker lead endocarditis.

BACKGROUND: The aim of this study was to investigate whether transvenous lead removal is safe and effective in patients with lead vegetations greater than 1 cm in size. METHODS: From 1991 to 2005, a total of 53 patients underwent pacemaker or ICD lead removal for vegetations. Transvenous lead removal using locking stylets and sheaths was performed in 30 patients (56.6%) and was found to be effective in 29 of those patients. In 1 patient, due to rupture of the lead, open heart removal of the ventricular lead remnant and tricuspid valve repair had to be performed due to persistent infection. In 23 of these patients, transesophageal echocardiography (TEE) verified vegetations greater than 1 cm in size. The remaining patients underwent primary lead removal using sternotomy and extracorporeal circulation (ECC). Pacemaker pocket infection was found in 16 patients (55.2%) of the transvenous study group and in 11 patients (45.8%) of the ECC group (P = 0.72). RESULTS: Perioperative mortality was 5.7% (3 patients); all of them underwent primary ECC removal and had severe endocarditis of the tricuspid valve. None of the patients who underwent transvenous lead removal died and there were no further complications such as pericardial tamponade or major pulmonary embolism requiring further interventions, even in patients demonstrating large vegetations. CONCLUSIONS: This study demonstrates that transvenous lead removal is a safe and highly effective procedure for the removal of infected pacemaker and ICD leads, even in patients with large vegetations. Embolism to the lung proceeds mainly without further complications; however, patients with vegetations that might obstruct a main stem of the pulmonary artery should undergo ECC removal.

Aged↗
PubMed2003

Lead generation--enhancing the success of drug discovery by investing in the hit to lead process.

Improving on the poor success rates in the drug discovery industry requires that knowledge-based decisions are made to advance or stop a lead candidate as early as possible in the discovery process. Failure to make such timely decisions on the rigorous selection of lead candidates has costly time and resource implications in downstream drug development. To meet this challenge dedicated 'hit to lead' groups have recently been established in many major pharmaceutical companies, and a key to the success of such groups is establishing a clear consistent process and rigorous metrics for lead quality. The importance of such a "Lead Generation" group within the drug discovery process will be highlighted with the aim of placing a greater level of emphasis in discovering and refining novel lead series with enhanced drug-like properties. This activity is facilitated by the application of productivity enhancing, integrated technologies coupled with the early evaluation of drug-like properties in the lead refinement process to ensure that a balanced activity - properties profile can be attained before committing to a full lead optimisation program. This article will survey the processes and tools employed in the hit to lead process in such a "Lead Generation" group in order to achieve these objectives, emphasising the possible gains in productivity through close, early interactions between chemistry and other expert groups.

Chemistry, Pharmaceutical↗
PubMed1988

A 20-year study of endocardial pacing lead EMT 588. Lead durability and nature of failure.

A report is presented of 1253 EMT 588 endocardial leads implanted in 1063 patients. The electrode surface area was large (47 mm2) in the 473 leads implanted during 1962-1973, and small (8-12 mm2) in the 780 leads implanted in 1974-1981. Replacement of 245 leads was necessary, in 187 cases due to lead failure and in 58 because of problems with normally functioning leads, such as infection. The highest lead failure rate occurred within the first 6 months after implantation, and was mostly caused by displacement and threshold increase. The dominating cause of late failure was lead lesion. The cumulative lead survival rates for the first and the second series were 88 and 94%, respectively after 1 year, 80 and 91% after 5 years, and 72 and 84% after 9 years. The polyethylene insulation proved to be the most vulnerable part of this lead. Insulation lesions could result in corrosion and/or fracture of the steel conductors. The chronic thresholds were largely stable.

Electrodes↗